Chee Xiong wrote:If Kingsrow and Cake are both very close to playing perfect checkers, maybe not on the level of today's Chinook but close enough.

Chee, both, Kingvsrow and Cake, are doing better than Chinook, either GAYP or 3-moves.

They have different moves, because these are two different programs written by two different authors and having a different engine and searching algorythm.

If you have two strong players - they make different moves, same for programs. In each position often enough there are 1-2-3 moves with identical or close strength and programs may prefer either way.

Neither program yet is close to "solve" the game at high level (make the best move). Chinook solved GAYP at low level (don't make a losing move) but this is not the same. In addition - nobody knows what does it mean - "best move". There are different opinion on this matter this is another reason why Kingsrow and Cake have different moves. It is vert possible that both, Kingsrow and Cake choice, are best at some point.

Alex_Moiseyev wrote:Chee, both, Kingvsrow and Cake, are doing better than Chinook, either GAYP or 3-moves.

I'm not entirely convinced of this, for a couple of reasons.

1. Every tournament game ever played by Chinook with > 6 piece endgame databases featured databases that were not correct. It was not until December 6, 2001 that Gil Dodgen and I had our 8-piece database statistics on win-loss-draw counts match every count of the Chinook team. Prior to that, Chinook had a few errors in its 7- and 8-piece databases. This number of errors was very small, but these errors could have widely influenced the play in several key games, including the legendary Round 1 pairing with Tinsley at the 1994 Nationals where Tinsley sprung a cook on the Chinook team. It was later discovered that Tinsley could have won the game, but the win was so complex, that even he missed it.

Chinook still had an incredible record. Think how much better it would have done with all of the bugs ironed out before playing its opponents!

2. People tend to forget Chinook never ran on a machine faster than 150 MHz. While it was a parallel searching program with many processors available on its strongest hardware configuration, such hardware would be crushed by top-of-the-line desktop machines of today. It is not a fair comparison to say that contemporary programs, which benefited tremendously from all of the papers published by the Chinook team, are any better than Chinook. If you disagree with this statement of mine, try building your databases on a machine with 32 Megabytes (NOt Gigabytes) of RAM, like the Chinook team, and see if you even have the patience to complete the project.

Don't forget: Nobody knew if endgame databases would even benefit a checkers program when Schaeffer first hypothesized about creating them. They certainly have no effect in the game of chess, even in 2016. Furthermore, with only the 4-piece or 6-piece databases, it was not well understood that the endgames could influence the play of the middlegame. It turns out, endgame databases probed in RAM from a distance have incredible power. If it were not for this pioneering research, all of us would be fiddling around with very weak programs, trying to figure out why they play so poorly.